Measurements of H evolution rates were used to study the lattice, and overall, diffusion rates in various alloys. Classical reaction kinetics were used to describe the movement of H in ferritic steels at 100 to 350C. The processes of H lattice diffusion and H release from traps in the metal were treated as being consecutive reactions, with the former being the rate-controlling one at high temperatures and the latter controlling at low temperatures. In the intermediate region, where neither process was predominant, there was a gradual transition from one mode of reaction to another. The true lattice and overall diffusivity coefficients were calculated in the intermediate-temperature region (table 63).
F.R.Coe, J.Moreton: Metal Science Journal, 1969, 3, 209-15
Table 61
Bulk Diffusion of 59Fe in Fe-Cr Alloys
Cr (wt%) | Temperature (C) | D (cm2/s) |
6.8 | 650 | 1.29 x 10-14 |
6.8 | 702 | 9.35 x 10-14 |
6.8 | 740 | 5.60 x 10-13 |
6.8 | 741 | 3.38 x 10-13 |
6.8 | 743 | 3.24 x 10-13 |
6.8 | 771 | 1.26 x 10-12 |
6.8 | 779 | 2.01 x 10-12 |
6.8 | 600 | 4.10 x 10-12 |
6.8 | 800 | 3.60 x 10-12 |
6.8 | 810 | 4.61 x 10-12 |
6.8 | 811 | 4.07 x 10-12 |
8.9 | 652 | 7.20 x 10-15 |
8.9 | 668 | 2.20 x 10-14 |
8.9 | 697 | 7.00 x 10-14 |
8.9 | 700 | 4.12 x 10-14 |
8.9 | 703 | 5.35 x 10-14 |
8.9 | 715 | 1.10 x 10-13 |
8.9 | 748 | 3.10 x 10-13 |
8.9 | 775 | 7.45 x 10-13 |
8.9 | 800 | 1.60 x 10-12 |
8.9 | 803 | 2.76 x 10-12 |
8.9 | 808 | 1.50 x 10-12 |